Display devices which control a display method by means of a parameter carried on a signal representative of a displayed image are conventionally known. For example, Japanese Laid-open Patent Application 11-122507 (Tokukaihei 11-122507, published on Apr. 30, 1999) discloses a video image signal processing device which is featured by the provision of an image processing means for implementing a stabilization control, scanning conversion, and other tasks based on a reference signal, a judgement signal, etc. inserted in the blanking interval of the video image signal. Another example is Japanese Laid-open Patent Application (Tokukaihei 10-133846, published on May 22, 1998) disclosing an image display device which controls brightness, display size, display position, and screen distortion correction based on a parameter, inserted in a display period of display data, which is acquired by sampling a signal produced by pulse counts based on horizontal and vertical synchronous signals.
However, to control a display method which is extensive and complex, a complex control parameter is required. The problem cannot be solved by inserting a parameter in a blanking interval as with the video image signal processing device disclosed in Tokukaihei 11-122507. As to the image display disclosed in Tokukaihei 10-133846, a parameter can be inserted in display data (in a display period); nevertheless, this constitution cannot deal with some really extensive and complex display methods which requires the insertion of complex parameter data. According to the constitution, since the parameter is acquired based on a horizontal synchronous signal and a vertical synchronous signal, inserting parameters in different positions in the display data adds to the complexity of the mechanism by which the parameters are derived from the display data.
The prior art technology is not readily applicable to the control of a display method of marked extensiveness and complexity of, for example, selecting among driver circuits (drivers) in a display device, turning on/off the backlight in a liquid crystal display, and switching between frame frequencies, and particularly so when more than one of the factors (operating driver, turn-on and -off of the backlight, frame frequency, etc.) which dictate the display method are to be controlled simultaneously to enable various display methods as required. Therefore, the prior art technology cannot readily produce display data with parameters inserted therein to control notably extensive and complex display methods. The mechanism (decoder) required to acquire the parameters from the display data is also complex.